1. Field of the Invention
This invention relates to polyalkylene oxide polymers and the use of these polymers as fiber and rubber lubricants. More particularly, this invention relates to polymers having an aromatic sulfone moiety incorporated into the polymers and of the use of these polymers as fiber and rubber lubricants having improved oxidative stability.
2. Description of the Prior Art
The conversion of nylon or polyester polymers into useful yarn for textile manufacture requires the use of a lubricant formulation called the "fiber finish" or "spin finish." The spin finish must control the yarn-to-metal friction to protect the newly spun fiber from fusion or breaks and, in the case of texturing, to insure that proper twist is transferred to the yarn. Synthetic fibers must be drawn and textured or bulked to yield optimum physical properties of strength, increased covering, pleasing hand, and greater warmth. During both texturing and bulking, the yarn is exposed to high temperatures. The demand for faster throughput is now requiring temperatures that approach 250.degree. C. thus placing increased stress on the finish to protect the fiber.
It is known to use polyoxyalkylene compounds such as block and heteric polymers of ethylene oxide and propylene oxide as spin finishes for the production of synthetic yarns. Heteric and block polyoxyalkylene compounds particularly from ethylene oxide and propylene oxide derived by polymerization with initiators such as Bisphenol A and tetrahydrofuran are known as spin finishes for the production of synthetic yarns.
The rubber industry is also a major market for such polyoxyalkylene compounds. An important application is for use as a lubricant in the production of tires and rubber hose. In the latter case, it is used as a lubricant to allow easy removal of radiator type hose from the mandrels used to form the hose during vulcanization.
A successful mandrel lubricant must provide good lubricity, be relatively oxidation resistant, produce minimal smoke, either be easily removed from the finished product or not leave a sticky residue, and show a low toxicity. Oxidative stability is important since the lubricant must survive the vulcanization process where the rubber is cured into the hose shape.
The rubber lubricant is often washed off the finished article and then recycled for reuse. Since the rubber hose is reinforced with fibers such as rayon or nylon the lubricant must not form decomposition products that will attack these fibers.
Currently acceptable oxidation stability is achieved by heavily stabilizing the polyoxyalkylene glycol with an antioxidant such as phenothiazine. However, this approach suffers from at least three problems, many antioxidants are moderately toxic, they may show only limited solubility in polyoxyalkylene glycol and, finally, they may decompose to strong acids which can hydrolyze the reinforcing fiber.
U.S. Pat. No. 4,094,797 discloses oxidation stable heteric or block copolymer polyoxyalkylene compositions suitable for the treatment of thermoplastic fibers, particularly polyester and nylon fibers, prior to the processing of such fibers. The polyoxyalkylene compounds are derived from lower alkylene oxides and can be initiated with a difunctional aromatic compound containing reactive hydrogens such as dihydroxyphenol and are capped on at least one end of the chain with an alpha-olefin epoxide or mixtures thereof. U.S. Pat. No. 4,134,841 discloses a fiber lubricant composition of enhanced heat stability which comprises a non-hindered polyphenol stabilizer and a polyether lubricant. The 4,4'-Thiodiphenol Technical Bulletin published by Crown Zellerbach, Chemical Products Division, Camas, Washington, discloses 4,4'-sulfonyldiphenol, a dihydroxydiphenylsulfone, which is the initiator for the compound of the instant invention.